Jim Michalak's Boat Designs

118 E Randall, Lebanon, IL 62254

A page of boat designs and essays.

(1October13) This issue will start a discussion about modifying boats from the given plans. The 15 October issue will continue the topic.



is out now, written by me and edited by Garth Battista of Breakaway Books. You might find it at your bookstore. If not check it out at the....


...which can now be found at Duckworks Magazine. You order with a shopping cart set up and pay with credit cards or by Paypal. Then Duckworks sends me an email about the order and then I send the plans right from me to you.


Sailing a brand new Scram Pram in Australia. Greg Flemming started the project, oh maybe ten years ago, and Ross Lillistone finished the details and made this cool youtube video http://www.youtube.com/watch?v=CnqvJB2ei7s&feature=youtu.be for us to watch. That is Paul Hernes at the tiller. I'm told this has a Fatcat2 sail rigged as a lug, smaller that the Scram drawings and essentially the same as the Blobster lug rig, but it appears to be excellent. Now I'm told it goes back to Greg for final painting. You can find Ross at www.baysidewoodenboats.com.au



Contact info:


Jim Michalak
118 E Randall,
Lebanon, IL 62254

Send $1 for info on 20 boats.



Modifying Boats 1


Not all boat designers care to see their plans modified. It's true some changes will be an invitation to disaster but here is how I feel about it. Most of you go to work each day and get told how to do everything, even though you may know a lot more about your job than the boss. So when you come home to follow your hobby you really don't want to be told to just follow the plans and shut up. Your hobby is your chance to be creative, maybe the only chance in your life. True, you could take your boat plans and add different trim or fittings. But a lot of you, probably most of you, are capable of a lot more than that. You could go higher, lower, wider, narrower, shorter or longer to start with. You might move everything around (maybe for a good reason), change the rig, etc, etc. Then you are on the road to being your own designer.

I recall in the old Small Boat Journal a reader writing to Phil Bolger, who had a regular boat design essay each issue, whether he could simply scale up a given design (of a dinghy in this case) to get something more suitable for his use. Phil said, "Yes, go right ahead." But added such a change would give a new design and that the reader, not Phil, would be the boat's designer. You see, almost any boat is a rework of a previous design.

I don't think Phil minded folks changing his plans much, as long as it was done with some thought and the builder would take the blame for any blunder. I don't mind it much either. It's cool to see what you guys will come up with!


As an example of a simple major change, let's say a fellow wants more interior room and is bound to raise the cabin roof a bit to gain it.

Now, if the boat is designed with plumb sides, like many Bolger box boats and I've followed along those lines, it isn't hard to figure out how to do it by looking at the plans. Like a normal box house, you make the walls higher and the roof will go with it. Take a look at the new Australian Scram Pram, a capture from the youtube video.....

Greg Flemming raised the roof a few inches in construction and I never noticed it! Ross Lillistone who completed the details said he wasn't sure of that also, but added it had plenty of headroom inside. It's a very simple change to make and can really enhance your interior life.

Now, if you have a hull with flared sides it won't be so easy. Because the boat gets wider as it gets higher and you will need to do a lot more head scratching and moan chair sitting to figure it out as you go. But I'll bet you can still do it.


But there are usually downsides to this. To me the real problem is that when you raise the cabin roof, you will need to raise the cockpit in order to see over the taller roof and when you do that the crew weight is also moved upward. On my boats the crew weight is a significant percentage of the total so the ability to stand up to a wind is reduced. Also coming into play here is that the sail rig would probably also be raised upward giving more heeling in a given wind. These things apply mostly to the usual sailing cabin boat, not so to a powerboat or a birdwatcher cabin type sailboat.

(By the way, raising the cabin roof should improve the self righting ability of a knock down sailboat because buoyancy up high is an important part of the righting equation. If you go too far with this you can get a sailboat that is very tender to sail - always wanting to tip over but always self righting.)

Another downside is the looks. Everybody wants a long lean looking boat. Even Bolger told me once that I needed to improve the looks of my boats. "Try making them longer and lower," he told me, the man who invented the LooseMoose! Herreshoff boats had that long lean look but as they would say about standing headroom, "What are you going to do in there - sleep standing up?" Best to not ask a designer to draw a boat around an outhouse either!

There is also the ever present problem involving the sizes of common materials. If your boat was designed for 4' deep sides, if you go deeper you will need to start scarfing plywood or something. Most designers keep this sort of material sizing in mind as they draw plans.


This is a really tough one. In olden days plans were simply lines drawings with a table of offsets that allowed the builder to draw full size on the shop floor. From there he made all the detail measurements he needed to lay out the real boat. Today's "instant" building, with all the major element shapes predefined on the drawings, eliminates that step (plus the need to make many forms and templates and have a shop with a floor that is capable of mounting all of those solidly). So I suppose in the olden days a fellow might say,"This boat is designed to be 4' wide but I'm gonna go to 6' wide by multiplying all the breadth dimensions by 1.5". That would work then but not with "instant" plans because all of the panel shapes are defined either by drafting or computer work to the original offsets. Make the boat wider or narrower and none of the pieces will fit even if you expanded the breadths of the bulkheads and such correctly.

I don't recall anyone wanting to modify one of my boats this way so perhaps it is not a big deal. But if you try to do it I'd say the kicker is that the roll stability of the boat will be affected way beyond what you might expect. I've never sat down to figure it out and that would be an interesting study. But perhaps the stability is affected as the cube of the beam, that is to say if you doubled the width of a hull, leaving all else the same, the new hull would be 8 times as stable in roll. That is not so much the worry as going narrower. Let's say you decide that you can stand up to fish in a boat that is 3' wide. Then you decide your next dreamboat will be a faster 2' wide. The new boat has less than 1/3 the roll stability of the old. ( I need to study this more but the fact is you can easily stand in a 3' wide Bolder Teal, and easily fall out of the 2' wide Bolger Light Dory as Phil said happened to him.)

So I guess my advice here is never modify a set of complete plans to go wider or narrower. Start with a fresh design on a new piece of paper.


This is fairly common. The usual effort is to move a cabin bulkhead to get more room in the cabin. If you aren't modifying the basic lines you should be able to scale off you new bulkhead from the plans and figure it out. The bevels of the new bulkhead may not be obvious but they are easily checked once you have the hull started, as in olden days when no plans included bevels.


I use bulkheads to divide the hull into sections and to force the crew to sit where they are supposed to. Doesn't always work but you have to try. So, for example, if you omit the bulkhead that forms a stern box and run the cockpit clear to the transom, and then use that extra to give a larger cabin, you can expect the boat to be way out of trim when the crew gets loaded towards the stern.

I think experienced boaters are always very aware of fore and aft trim and new boaters are never aware of it. So you can almost tell how salty a sailor is by how he trims his boat. The late and great Thomas Firth Jones had a cool story about this in his book "Boats To Go". As I recall, he designed and built a mid size sail cruiser for a customer. He was very pleased with the results but the buyer was not. The buyer insisted on wheel steering instead of tiller steering and insisted the boat be modified. Aside for the cost of the wheel steering Jones was dreadful of its weight, plus the skipper's weight, being in the extreme stern of the boat. But the boat was modified for the buyer. Tom said the result was the terrible trim he predicted, and that the buyer was completely happy!

And, by the way, leaving out buoyancy boxes that are supposed to save your ass in a swamping is not thoughtful, but it is done all the time I'm afraid. I might add that most buoyancy boxes are minimal for this, we really should be designing them larger as I saw demonstrated at the SailOK in 2012. I think that this sort of safety design is an art to itself and I am not an artist. Not only must there be enough emergency buoyancy, it all has to be in the right places to support the swamped boat in a way useful for self recovery. Having it all in the stern or the bow is not the correct answer.

Actually there is more to the bulkhead thing in that bulkheads are also there to distribute sailing loads, especially mast and leeboard (or daggerboard or centerboard or keel) loads. I've seen some distiguished boats with problems this way - they get sagging rigs, loose keels, and such over time. Not so much a problem in olden days when boats were made of thick lumber (although the old carvel planked hulls would warp mightily over time) and the sailing rigs were much less taut than today's. So if you move a bulkhead that supports a mast fitting, maybe the mast needs to be moved with it. It's something you need to consider. I'll get to that later in the series because it seems to be the main trap that hull modifiers fall into, at least for my designs.

It's closely related to the "longer and shorter" of it and we will get to that next issue....




Larsboat was built by Lars Hasselgren to replace a Folboat that had finally met its end. Lars wanted capacity for two, plus decking, as with his old boat.

I took Toto and lengthened it with a 30" plug in the middle to gain capacity. But lengthening a hull with a straight plug like this usually improves a boat in almost every way and Larsboat should be faster than Toto in good conditions. In this case the plug meant I didn't have to refigure the shape of the twisted bow panels as I would if I'd lengthened Toto with an overall stretch. (I can figure twisted panels pretty reliably now, but not back when Toto and Larsboat were drawn.)

The decking was quite simple because even the original Toto could take a forward deck of flat sheets with a center peak. I should add that I feel the decking is very optional. This prototype weighs 61 pounds and deleting the deck might cut another 10 pounds or so. The undecked boat also would have a better cartopping shape. I'd keep the stern chamber. It will ease your mind about taking a big wave over the stern.

This would be a preferred project for someonw who intends to do a lot of cruising and camping. In the Toto camping I've done the sleeping room has been OK, but the storage is limited. Larsboat would be better both because of increased capacity and because there is dry storage under the bow deck.


The basic hull is taped seam construction needing four sheets of 1/4" plywood for the decked version and three sheets for the undecked version. No jigs or lofting required. Plans are two blueprints with keyed instructions for $20.

The photo above is of Bob Smithson's Larsboat. He customized the decking a bit. I think he also built the boat of 1/8" ply to save weight. I've forgotten what his boat weighed but he did say it was sufficiently rigid for him.

Bob Hoyle built this one without a deck down in Florida:

Paul Moffitt built this one. You can see this is a much better two person boat than the shorter Toto:

And remember Garth Battista's vertical Larsboat?

And the old outboard motor guru Max Wawrzniak often goes for a paddle in his Larsboat:

Larsboat plans are $20.


Prototype News

Some of you may know that in addition to the one buck catalog which now contains 20 "done" boats, I offer another catalog of 20 unbuilt prototypes. The buck catalog has on its last page a list and brief description of the boats currently in the Catalog of Prototypes. That catalog also contains some articles that I wrote for Messing About In Boats and Boatbuilder magazines. The Catalog of Prototypes costs $3. The both together amount to 50 pages for $4, an offer you may have seen in Woodenboat ads. Payment must be in US funds. The banks here won't accept anything else. (I've got a little stash of foreign currency that I can admire but not spend.) I'm way too small for credit cards.

I think David Hahn's Out West Picara is the winner of the Picara race. Shown here on its first sail except there was no wind. Hopefully more later. (Not sure if a polytarp sail is suitable for a boat this heavy.

Here is a Musicbox2 out West.

This is Ted Arkey's Jukebox2 down in Sydney. Shown with the "ketchooner" rig, featuring his own polytarp sails, that is shown on the plans. Should have a sailing report soon.

And the Vole in New York is Garth Battista's of www.breakawaybooks.com, printer of my book and Max's old outboard book and many other fine sports books. Beautiful job! Garth is using a small lug rig for sail, not the sharpie sprit sail shown on the plans, so I will continue to carry the design as a prototype boat. But he has used it extensively on his Bahamas trip towed behind his Cormorant. Sort of like having a compact car towed behind an RV.

And a Deansbox seen in Texas:

Another prototype Twister is well along:

And the first D'arcy Bryn is taped and bottom painted. You can follow the builder's progress at http://moffitt1.wordpress.com/ ....








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